1. Field of the Invention
The invention relates to a pixel array, and more particularly, to a pixel array which enhances display qualities of a display device.
2. Description of Related Art
In view of current display technologies, liquid crystal display panels, which have superior characteristics such as good space utilization, low power consumption, and being free of radiation, have gradually become the mainstream products in the market. In order to broaden the range of viewing angles of the liquid crystal display panels, a pixel array has been provided.
FIG. 1 shows an equivalent circuit diagram of a conventional pixel array. Referring to FIG. 1, a pixel array 100 includes a plurality of scan lines GLi, GLi+1, . . . , a plurality of data lines DLi, DLi+1, . . . , and a plurality of pixels structures PIX1, PIX2, PIX3, PIX4, . . . , wherein each of the pixel structures PIX1, PIX2, PIX3, PIX4, . . . includes a first pixel unit PM and a second pixel unit PS. Each of the first pixel units PM includes a thin film transistor (TFT) T and a liquid crystal capacitor CLC1′, and each of the second pixel units PS includes another liquid crystal capacitor CLC2′ and a coupling capacitor CC′.
In detail, through a gate end and a first source/drain end of each of the TFTs T, the pixel structure PIX1 is coupled to the scan line GLi and the data line DLi, the pixel structure PIX2 is coupled to the scan line GLi and the data line DLi+1. The pixel structure PIX3 is coupled to the scan line GLi+1 and the data line DLi, and the pixel structure PIX4 is coupled to the scan line GLi+1 and the data line DLi+1. Using the pixel structure PIX1 as an example, the liquid crystal capacitor CLC1′ in the first pixel unit PM thereof is coupled between a second source/drain end of the TFT T and a common voltage Vcom, and the liquid crystal capacitor CLC2′ in the second pixel unit PS is coupled between the coupling capacitor CC′ and the common voltage V. In practice, a storage capacitor Cst is generally disposed between the second source/drain end of the TFT T and the common voltage Vcom, so as to maintain the voltage level of the liquid crystal capacitor CLC1′.
As know from the equivalent circuit diagram shown in FIG. 1, a relationship between a voltage V1 and a voltage V2 is as shown in the following equation.
      V    2    =            V      1        ⁢                  C        C        ′                              C                      LC            ⁢                                                  ⁢            2                    ′                +                  C          C          ′                    
A voltage difference between the first pixel unit PM and the second pixel unit PS when they are displaying is shown as the difference between the two voltages V1 and V2 in the above equation. Through the first and second pixel units PM and PS having different voltage values when displaying, the respective liquid crystal molecules in the first and second pixel units PM and PS have different tilting angles, thereby broadening the range of viewing angles of the liquid crystal display panel.
However, the coupling capacitor CC′ is disposed in the second pixel unit PS in a floating method. This design causes residual charges in the coupling capacitor CC′, thereby causing residual images on the displayed frame and lowering the display qualities.